Wireless telegraphy.



No. 841,386. PATENTED JAN. 15, 1907. L. DE FOREST.

WIRELESS TELEGRAPHY. APPLICATION FILED AUG. 27. 1906v 2 SHEETSSHEET 2 was- 2 LEE DE FOREST, QFY'NEW YORK, .N. Y.

WIRELESS TELEGRAPHY'. 5

To all whom it may concern.-

Be it known that I, LEE nE Foans'r, a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented anew and useful Improvement in Wireless Telegraphy,

of which the following is a-specification.

My invention relates to wireless telegraphy and more particularly to an oscillation-detector which, in addition to performing the usual functions of sueh'detectors, may be used as a tuning device and as a static valve, and which has a variety of other uses. 1

l have discovered that ifthe gaseous medium intervening between separated electrodes be put into a condition of molecular activity, as by heating thesame or otherwise, said medium becomes highly sensitive to electrical oscillations, as more fully set forth in my application, Serial No. 243,913.

l have shown in my application, Serial X: b. 300,975, that the sensitiveness of an oscillation d tector comprising electrodes sepa rated by such sensitive gaseous medium may be varied by the action of a magnetic held. so that the response of said'detector per se is a function of a characteristic, such as the frequency, ofthe electrical oscillations operating upon the same. Thus, for certain frequencies a magnetic field of given strength will greatly decrease the sensitiveness of the detector and render it practically non-responsive, while for other frequencies the same magnetic field will greatly increase the sensitiveness of the d tector. In short, said detector per se may be made selectively responsive without having recourse to tuned or resonant circuits, so that the use of such circuits may be dispensed with and the detector itself employed to perform the functions heretofore effected by said circuits.

. 'lhe subject-matter of the present invention is an oscillation' detector'which. like that above referred to, may be made selectively responsive to electrical oscillations hav ing a given frequency or electrical irate of vibration but which does not require .a proximate magneticjield forthis purpose and which also may be made selectively re sponsive to electrical oscillations having a given spark, or wave-tram, frequency-that is to say, may be so adjusted that its re.

sponse to electricaloscillations is 'a'function of the number of groups or trains of waves per second, irrespective of the electrical frequency of such. w aves, I r

Specification of Letters Patent. Application filed August 27, 1906. Serial in, 332,213.

Patented Jan, 15, 1907;

By virtue of the selective properties of my 'fortlrin my United States Letters Patent Nos. 827,523. and 827,524, dated July 3], 1900.

My invention may best be understood by having reference to the drawin s which accompany and form a part of t IiS specification and which diagrammatically illustrate four embodiments ,thereof which have successfully been employed; but I do not'wish to limit myself to .1110 delails shown therein inasmuch as many other forms of construction and arrangement of circuits embodying the principles of my invention, as particularly pointed out in the apiended claims, will readily occur to those skilled in the art. In the drawings, Figure l'represents a simple form of'my oscillation-detector conducts ively connected with a receiving-antemia; Fig. 2 represents a detail of construction usedin connec'ition with the detectors shown in Figs. 1, 3 and 4. Fig.3 represents a modification of the detector shown in Fig. 1 in which the detector is energized by an electric field developer-lby the oscillations to be detected. Fi 4 represents a further modification in which the detector is energized by lnited States Leta magnetic field created by the oscillations to be. detected.

In the figures,.Ais areceiving-antenna. E is an earth connection.

M is a transformer, ofwhich I, and I are the-primary and semiidary windings.

B B are batteries. R R are resistances. L L are ihductances.

T is a telephone or other signal-indicating device. V

1) represents an evacuated vessel of glass or other suitable material having two separated electrodes F and F between which u1- tervi-nes the gaseous medium which, when sufficiently heated or otherwise made highly conducting, forms the sensitive element of my oscillation-detector. While various means may be employed for heatlng sa d'gaseous medium I. find it convenient to em loy electrical means and, therefore, I pre er to employ as the electrode F a filament of carbon or metal and to connect the same in series with a battery B and a rheostat R.

pecially one of tantalum, renders the oscillation-detector much more sensitive than one of carbon. 7

The electrode F may consist of a nonheated metallic bodysuch, as shown in the present instance, as the wings or plates F F secured to the metallic base2, which may be supported by the upwardly-extending portion 3 of the vessel D, although any suitable means may be used to support the electrodes F within said vessel.

While 1 have shown and described the electrode F as consisting of two wings .or flat plates, it will be understood that said elecone flat plate.

The evacuated vessel D ma be provided with a screw-socket 5 after t e manner of ordinary incandescent lamps, and one end ofthe filament F may be conductively -con nected thereto while the other end may be insulated therefrom andconductively connected to the contact-piece 4 in'the base of the socket. In such case the terminals of the heating battery B are connected respec-. tively to the socket at b and to the contact piece 4.

The tern linals of the local circuit, which includes the battery B and signal-indicating device, such as the telephone T,- are ,connected respectively to the electrodes F and F at a and'b. Means may be included in or associated with the local circuit for varyingthe potential developed by the local circuit B between the oints'a and b. For this purpose the num er of cells which make up-the attery B may be varied, or the adjustable resistance R, which, with the battery, constitutes a potentiometer, may be used.

The oscillation-detector, as above described, may be associated with the receiving system in a variety of ways now well known in the art by connecting the electrode to one of the terminals of the source of oscillations and the electrode F to the other term:-

ascertained that a filament of metal, es

nal thereof. In the present instance the an tenna A is connected to the electrode F by a leading-in wire which is connected to the base 2 and which is sealed in the vessel D at a, and the earth-connector is connected to the electrode F through the socket5 and the conductor b c.

It is preferable that the positive pole of the battery B should be connected to the electrode' F, and better results are obtained if the ncgativepole of the battery B be con nected to that end of the filament F to which.

the positive pole of the battery Bis connected, (shown in Figs. 1,3, and 4% that end of said filament which is connected to the screwsocket.)

By regulating and adjusting the amount of heating-current flowing in the circuit of the battery B, the sensitiveness of my detector may be varied, so that the response of the detector per se will be a function of the freamplitude of the heating-current must be determined empirically, as by adjusting the '-rheostat R, because a number of factors such, for example, the se aration of the electrodes F F and the di erence of potential developed .by battery B across the points a b, are involved.

By regulatin and adjusting the potential.

For tuning the oscillation-detector to oscillations of given electrical frequency, the

impressed by t 1e battery 13 across the eleetrodes F F, the sensitlveness of the detector may be varied so that the response of the detector'per se, other things being 0 ual, will be a function not on? of the electrica frequency or wave length 0 the oscillations operating upon the detector, but also of the spark frequency which,vcaeterts pambus, ls'a measure of the total energy received, and the detector itself, as distinuished from a circuit tuned electrically to e ectrical or to spark frequency and from a mechanism tuned mechanicall or acoustically to spark frequency, will be se ectively responsive to oscillations having a given electrical frequency, and also to oscillations having a given s )ark frequency irres eetive of their electricalfrequency or wave en th. Thus, with a given separation of the e ectrodes F F and a given am litude of heating-current flowing through t e filament F, I have been able by merely varying the otential of the battery B to attunetheoscil ationdetector to the oscillations develo ed in the receiving system by one of severe transmitting systems and to receive the energy thereof to the exclusion of the energies of the oselement 1 call the audion,

battery B upon t cillations developed therein by the other of said transmitting systems, even when the several sets of OSUllltltlOIlS-llfid the same electrical frequency and wavelength, butdif in average energy Ilere also the adiotentialimpressed by the fercd in sip ark frequency or conveyer per unit of time. JUStIIIOIlt of the determined empirically.

By virtue of the selective properties of my detector, as above set forth, I am enabled to effect by the detector itself a method of double-tuning which affords the greatest security from waves the energy of which is not intcndedto affect the detector as well as from atmospheric or static, electricity and other disturbing electrical forces.

As above mentioned, the sensitiveness of my oscillation detector, which in common with others of my invention employing a conducting gaseous medium as the sensitive is a function of the separation of the'electrodes or of-the length of the sensitive conducting gaseous medium; but I find that here again the frequency is a determining factor, so that by varying the separation of the electrodes 1 can make the response of the audion a function of the. frequency. In other-words, by suitably varying the length of the interelectrode medium, other adjustments, suchas those of the batteries B B, remaining unchanged, I am enabled to make the audion per Se selectively responsive'to oscillations of a given frequency independently of the usual tuned or resonant circuit heretofore employed in wireless telegraphy as a current or oscillation selector.

A -convenient means of varying the distance between the electrodes F F is to hinge the wings which constitute the electrode F to the base 2 as by the hinges 1 1. By approaching the magnets 6 6 to the inverted tube, as shown in Fig. 2, the wings, which may be made wholly or partly ofjiron, will open outwardly away from the filament and therebyincrease the path of' the conducting ions in the interclcctrode medium.

WVhen the audion is to'be attuned to oscillations :of a given frequency by varying the separation of the electrodes, the ad justment produced by the magncts'6 6 must be empirically determined, just as the adjustments of the batteries B B above referred to are purely empirical.

It will be understood that each of the three methods above set forth for varying the response of the audion in accordance.

witli'the electrical frequency and the spark frequency of the oscillations to be detected may be separately employed and also that any two or all threeof said methods may be. used conjointly. For example, by appro priately varying the separation of the elf-cie electrodes F F must be trodes F F and the amplitude of the .heating-current from the battery-B, the audion maybe madeselectively responsive to waves of a given electrical frequency, and then by the regulation and adjustment of the potential impressed upon the audion by the battery B, the audion may be made to select a particular one of a number of sets of waves all having the said electrical frequency and wave length, buteach set having a spark frequency different from that of any other set.

and 4 are identical in construction with those above described in connection with Figs. 1 and 2, and differ therefrom merely in the manner in which theyarcassociated with the source of oscillations to be detected.

In Fig. 3, 7 represents .a metallic member 'brou'ghtinto proximity with the vessel 1) and shownin the present instance as a cylinder surrounding said vessel. terminal of the oscillation source which in the present instance is shown as a circuit including the secondary of the transformer M, isconductively connected to the cylinder 7 at the point d,'while the other terminal may be connected to either one of the electrodes F or F. and in the present instance is shown as, connected to the electrode F through the socket 5 and conductor'b c. In this case the. oscillating electric field developed by the electrical oscillations in the secondary circuit, which includes the secondary winding 1 operates to iilter the conducting properties of the sensitive conducting gaseous medium in the vessel I) and thereby to vary the current flowing in the local circuit which in cludes the telephone T, just as in. the case of the system shown in Fig. 1 in which the ter-" minals of the. oscillation source are connected directly to the interelectrode medium.

The arrangemenLshoWn in Fig. 3afl'ords a fourth method of rendering the audion selectively responsive, for in addition to the three methods above, set forth in connection with Figs. 1 and 2 I find that, other things being equal, the response of the audion to oscillations of a given frequency is a function of the area of thesurface of the number 7 and of the separation thereof from the elements within the vessel 1). I

If the form shown in Fig. 3 be employed, the cylinder 7 may be moved with respect to the axis of the vessel D until, cazteris par'ilms, the response of the audion is a maximum for oscillations of argiven frequency. It will be understood of course that the separation of the electrodes F, F, and the values of the resistances R, R, of the audion shown in Fig: 3 may all be varied in the manner abovee'x} plamed in connection with Flgs. 1 and 2.

When the connections shown in Fig. 3 are used I find that the quality of the sound produced in the telephone T is quite different In this case one 1 from that produced therein when the connecin Fig. 4 selectively responsive.

tions shown in Fig. 1 are used, although the sounds may be, and under the same conditions are, of equal intensity. When the connections shown in Fig. l areemployed, the

sounds produced by the telephone are sharp 'and crackling, as is the case where various other forms of oscillation-detector are emv ployed; but when the connections shown in Fig. 3 are-used, the sounds produced by the telephone, under the same conditions as before, arc-mullled or drummy. This latter sound is distinctive and is notprodueed by the use of any other form of oscll used very nearly imitate'the sounds produced therein by static disturbances or atmospheric electricity.

V In the arrangement shown in Fig. 4 the audion is energized by the oscillating magnetic field developed by the passage of the oscillations to be detected through the coil L which surrounds the sensitive conducting gaseous medium and which in the present instance is wound around the outside of the tube. This coil preferably is made adjustable, as by the contacts f and g, and the antenna A may include an inducta'nce L havin r an ad justingcontact e. It will be understoo that the adjustments of the separation of the electrodes F, F, of the amplitude of the heating-current and of the value of the potential impressed between the points a and b, asset forth above in connection with Fig. 1, may also be employed to render the audion shown I have ascertained also that the variation of the magnetic field created by the passage of oscillations through the coil L Varies the response of the audion, other things being the same, and furthermore that this variation also is a function of fre uency. In other words, having adjusted t e audion to be most responsive to oscillations of given frequency in the manner above described in connection with Fig. 1, there may be found em irically a certain position for the contacts j or g, at which for oscillations of a said frequency the response of the detector is a maximum.

The s ntonizing-inductance L, or other electrical tuning device, may be employed in connection with any of the several embodiments of my present invention so as to combine the selectivity of the antenna or tuned receivin -circuit with the'selective properties of t e.oscillation-detectoritself, am in suchcases I have found the selectivity of a receiving s stem so constructed to be very high dee which is conducting or a gas whose conductivity is greater than that of air under an at tenuated pressure.

- I claim 1. An electrical-oscillation -selecting device comprising a vessel, a filament sealed in said vessel, a source of electric current connectedin series with said filament, means for varying the amplitude of said current, where by said device is rendered selective of electrical oscillations having a given electrical frequency, a member of conducting material inclosed within said vessel and a circuit connecting said member with said filament.

2. An electrical -oscillationselectin vice comprising a vessel, a filament sea ed in said vessel, a source of electric current connected in series with said filament, a member of conducting material inclosed within said vessel, a circuit connecting said member with said filament, a source of electromotive force associated with said circuit and means for varying said electromotive force, whereby said device is rendered-selective of electrical oscillations havin a given spark frequency.

3; An electrica -oscillationselect1n device comprising a vessel, a filament sea ed in said vessel, a source of electric current connected in series with said filament, means for varyin the amplitude of said current, whereby sai device is rendered selective of electrical oscillations having a given electrical frequency, a member of conducting material inclosed within said vessel, a circuit connectingsaid member and said filament, a source of ele'ctromotive force associated with said circuit andmeans for varying said electromotive force, whereby said device is rendered selective of electrical oscillations having a iven spark frequency.

4. in electrical-oscillation-selecting de vice comprising a vessel inclo'sing a gaseous medium maintained in a condition of molecular activity. two electrodes inclosed within said vessel, and means for varying the separation of said electrodes.

5. An electrical-oscillatiou-selecting device c'omprisiug a vessel inclosing a gaseous medium maintained in a condition of molecular activity, two electrodes inclosed within said Vessel, and means outside said vessel for varying the separation of said electrodes.

6. An electrical-oscillation selectin vice comprising a vessel, a filament sea ed in said vessel, a source of electric current connected in series with said filament, a member of conducting material inclosed Within said vessel, a circuit connecting said filament and loo said member and means for varying the sepavice comprising a vessel, a filamentsealed in sai said vessel, a source of electric current connected in series with said filament, and means for varying the amplitude of said current, whereby said device is rendered selective of electrical oscillations having a given electrical frequency.

8. An electrical oscillation selecting device comprising a vessel, a filament sealed iii said vessel, a source of electric current connected in series with said filament, a member of conducting material inclosed Within said vessel, a circuit connecting said filament with said member, a source of electromotive force associated with said circuit, means for vary ing said electromotive force and meansfor var ing the separation of said filament and sai member.

9. An electrical-oscillationselecting device comprising a vessel, a filament sealed in said vessel, a source of electric current connected in series with said filament, means for varying the amplitude of said current, Whereby said device is renderedselective of electrical oscillations having a given electrical frequency, a conductor inclosed within said vessel, a circuit connecting said conductor and filament, )3. source of electromotive force associated with said circuit and means for var 'ng said electromotive force, whereby device is rendered selective of electrical oscillations having .a given spark frequency. 10. An oscillation-detector and means whereby said detector per se is rendered selective of electrical oscillations having a given 11. by said detector per se is rendered selective of electrical oscillations having a given elec- .trical frequency and means whereby said detector per se is rendered selective to electrical oscillations having a given spark frequency.

12-. An electrical-oscillation-selectmg device comprising a vessel containing a sensitive conducting gaseous medium, two electrodes within said vessel, a local circuit connecting said electrodes, a receiving-circuit having one terminal connected with one of said electrodes, a conducting member out side said vessel and'movable withrespect thereto, and an electrical connection from the other terminal of said receiving-circuit to said conducting member.

spgrk frequency.

13. An electrical-oscillation sclecting (15-- vice comprising a vessel inclosing a gaseous medium maintained in a condition of molecular activity, twoelectrodes inclosedwithin saiil/vesscl, means for im ressing an electrical potential upon saic electrodes, and v means for varying said potential.

14. An electricahoscillation-sclocting device comprising a vessel inclosing a gaseous medium, an electrode within said vessel, means for heating said olectrodcfmcans for regulating the temperature thereof, a second- .oscillation-detector, means whereelectrode inclosed within said vessel and a circuit connecting said electrodes.

15. An electrical oscillation-selecting device comprisin a vessel inclosing a gaseous medium, an eectrode within said vessel, means for heating said electrode, means for regulating the temperature thereof, a second electrode inclosed within said vessel, means for impressing an electrical potential upon said electrodes and means for varying said potential. c p

16. An electrical-oscillation-selecting device comprising a vessel inclosing a gaseous medium maintained in a condition of molec ular activlty, two electrodes inclosed within saidvessel, a local circuit-connecting sald electrodes and means for varying the separation of said electrodes.

- 17. An electrical-oscillation-selecting de} vice comprisin a vessel inclosing a gaseous medium, an e ectrode within said vessel, means for heating said electrode, means for varying the temperature thereof, a second electrode inclosed within said vessel and means for varying the separation of said electrodes. I 18. An electrical-oscillation-selecting device comprisin a vessel inclosing a gaseous medium, an e ectrode within said vessel, means for heating said electrode, means for varying the temperature thereof, a second 5 electrode inclosed within said vessel, a circuit connecting said electrodes, an adjustable. source of e'lectromotive force associated with said electrodes, and means for varying the' separation of said electrodes. zoo 19. An electrical-oscillation detector comprising a vessel'inclosing a gaseous medium, means for maintaining said gaseous medium in a condition'of molecular activity, a memher in proximity to said vessel,'and an oscil- 165' lation circuit electrically-connected to said member and to said gaseous medlum.

20. electrical-oscillation-selecting. de-' vice comprising a vessel inclosing a gaseous medium, means for heating said medium,

and means 'for varying the temperature thereof, whereby said device is rendered selective .of electrical oscillations having a given electrical frequency.

21. An oscillation-detector comprising two 1 1 5 'conductively-connected flat; plates of con ducting materialinclosed within an evacuated vessel, an electrode sealed within said vessel and located between said plates, and means for heating said electrode.

22. An oscillation-detector comprising'two conductivcly-connected flatv plates of con-'- ducting material inclosedwithin an cvacu ated vessel, a metallic filament sealed within saidvessel and located between said plates, l2 5 and means for heating said filament.

23. An oscillation-detector comprising two conduct ivelyconnected flat plates of conducting material inclosed within an evacufiatplates of conducting material inclosed ate-d vessel, a filament of tantalum sealed with n an evacuated vessel, a filament sealed within said vessel and located between said within said vessel and located between said plates, and means for heating said filament. plates, and means for heating said filament. I5 5 24. An oscillation-detector eomprisin two In testimony whereof I have hereunto subflat plates of conducting material inclosed scribed mvname this 24th day of August, within an evacuated vessel, an electrode 1906.

sealed'within said vessel and located be- LEE DE FOREST. tween said plates, andmeans for heating Witnesses: 1o said electrode. GE'o. E. TERRY,

25. An oscillation-detector comprising two GEO. K. WOODWORTH. 

